void main() {
  Person data = new Person('张三');
  print(data.name);
  Info info = Info.withInfo('阿三', 20);
  print({info.name, info.age});
}

class Person {
  String? name;
  int? age;
  Person(this.name);
}

class Info {
  String? name;
  int? age;
  Info.withInfo(this.name, this.age);
}
